Analysis of state and national policies that affect racial/ethnic disparities in healthcare is a research topic of specific interest for the NIMHD, and simulated consumer (audit) studies have emerged as an important methodology for measuring disparities and assessing the effects of public and private policies on disparities. By experimentally controlling for consumer characteristics, such studies avoid the responder biases associated with surveys and the limitations of utilization analyses (e.g., controlling for differences in health and treatment preferences). The Longitudinal Access to Physicians Study (LAPS) in this proposal is innovative because it is the first to audit the effects of race/ethnicit and sex on access, to audit a national random sample of primary care physicians, and to audit access for Medicare patients. In LAPS, student research assistants (SRAs) call the offices of primary care physicians to request appointment information for a purported uncle or aunt. Each physician is randomly assigned a male or female patient profile with an insurance type and a name signaling race/ethnicity. The central hypotheses underlying this proposal are: a) Increases in the demand for physician services due to the Affordable Care Act's (ACA) major insurance expansion will initially decrease appointment availability, but that appointment availability will improve over time as the health care system adjusts to the insurance expansion; b) The decrease in appointment availability will be smaller in states that experience smaller insurance expansions and have more generous physician reimbursement policies; and c) Changes in access will be differ for population subgroups leading to changes in disparities in access. These hypotheses will be tested by pursuing two specific aims: 1) Measuring changes in 2014, 2015, and 2016 from ACA- baseline in appointment availability and in disparities in appointment availability; and 2) Measuring changes in 2014, 2015, and 2016 from ACA-baseline in appointment availability and in disparities in appointment availability in states with different Medicaid expansion and reimbursement policies. The proposed research is significant because the results of the study are expected to provide strong evidence of the effects of the ACA as well as insurance and reimbursement-related state policies on disparities in access to primary care physicians. This research is relevant to the goals of the NIMHD because its results are expected to enable policymakers to better identify factors contributing to disparities and design effective policies for their amelioration. This study will also fulfill the goal of research enhancement by strengthening the research environment at Portland State University, the largest and most diverse university in Oregon. All SRAs learn the importance of ethics, human subjects' protections, and consistency in research. Some SRAs also learn about study design, statistical methods, and the broader literature on disparities. This study will create opportunitie for greater student participation and interest in disparities research.